|
| Place of Origin | JAPAN |
| Brand Name | FANUC |
| Certification | CE ROHS |
| Model Number | A20B-3900-0074 |
The FANUC A20B-3900-0074 is best described as a 4MB memory module for FANUC i-Series controls.
Replacement listings commonly associate it with 16i, 18i, 20i, and 21i systems and describe it as a DIMM-style memory module used inside the CNC rather than in the amplifier or operator-panel side of the machine.
On a product page, the clearest positioning for this model is as an internal control-memory replacement board.
That framing is more useful than calling it a generic PCB, because the board is searched and selected mainly by part number, memory size, and control family.
In service work, this kind of module matters when the original control platform is still productive and the correct memory board is needed to preserve the intended hardware layout.
| Parameter | Value |
|---|---|
| Part Number | A20B-3900-0074 |
| Brand | FANUC |
| Product Type | Memory Module |
| Memory Capacity | 4MB |
| Module Style | DIMM memory module |
| Commonly Listed Controls | 16i / 18i / 20i / 21i |
| Product Family | A20B-3900 series |
| Typical Use | CNC memory replacement |
What makes the A20B-3900-0074 useful in industrial service is not just the 4MB size.
Its real value is that it belongs to a specific memory position inside older FANUC i-Series controls. That means buyers typically need it for exact board-level replacement, not for broad “upgrade” use.
When a control still has years of productive life left, a correct module swap is often the most practical way to restore the original memory path without changing the wider CNC platform.
This is an engineering inference grounded in the board being sold specifically as a 4MB DIMM memory module for i-Series controls.
Q1: What is the A20B-3900-0074 used for in a FANUC control?
It is used as a 4MB internal memory module in FANUC i-Series controls such as 16i, 18i, 20i, and 21i.
In practical terms, that places it in the controller memory structure rather than in the servo amplifier, spindle drive, or front-panel section.
Q2: Why is exact part-number matching important for this module?
Because memory modules in the A20B-3900 family can look similar while still carrying different capacities or intended fits.
For A20B-3900-0074, the 4MB DIMM identity is part of what defines the board, so selecting by exact model number is safer than choosing by appearance or family name alone.
Q3: Is this mainly a repair-market product or a new-system product?
It is much more relevant to repair, replacement, and long-life support than to new machine development.
The way it is listed and sold today is centered on replacement inventory for existing i-Series machines, which is typical for board-level CNC memory parts.
Q4: Where is this module installed inside the control?
Listings describe it as a DIMM memory module for FANUC i controls, which indicates an internal master-board or memory-board installation context rather than a field-wired accessory location. In service work, that means the receiving socket and surrounding board area deserve inspection before replacement.
This installation advice is an engineering best-practice inference based on the DIMM-style description.
Q5: What should be checked before replacing A20B-3900-0074?
A technician should verify the exact installed board number, confirm the target control family, and make sure the observed fault really points to the memory section rather than to the main board or a separate software problem.
After installation, stable startup and normal control behavior should be confirmed before returning the machine to production.
The final verification steps are standard engineering practice supported by the module’s role as an internal i-Series memory board.
Contact Us at Any Time
